Solution-Processed Self-Powered Transparent Ultraviolet Photodetectors with Ultrafast Response Speed for High-Performance Communication System

Transparent ultraviolet (UV) photodetectors are an essential component of next-generation see-through electronics. However, the current photodetectors often suffer from relatively slow response speeds and high driving voltages. Here, all-solution-processed UV photodetectors are reported that are facilely prepared from environmentally friendly and abundant materials. The UV photodetectors are composed of a titanium dioxide thin film as the photosensitive layer sandwiched between two different transparent electrodes to form asymmetric Schottky junctions. The photodetector with high optical transparency can operate at zero bias because of spontaneous separation of photogenerated electron-hole pairs by the built-in electric field. The resulting self-powered photodetector displays high sensitivity to broadband UV light (200-400 nm). In particular, an ultrafast response speed up to 44 ns is obtained, representing a significant improvement over those of the conventional transparent photodetectors. Moreover, the photodetector has been successfully applied, for the first time, in a UV communication system as the self-powered signal receiver. This work uniquely combines the features of high optical transparency and self-power ability into UV photodetectors and would enable a broad range of optoelectronic applications.